Forget charity wristbands: little, metal military-style dog tags are about to become the Next Big Thing in fundraising fashion, pioneered by helpline charity Samaritans. These days, driven by increasing competition for the caring public's pound, charity fundraisers have to be trendsetters.

"We've done wristbands - along with many other charities. Wristbands are very firmly on the way out," says Samaritans deputy director of fundraising and external affairs Rebecca Seedhouse. This is why the charity was looking for something new and different. "We consulted the fashion industry quite closely about what trends are coming in."

Fundraisers must look ahead for ideas that will keep the public interested and giving, and in a crowded market, every charity wants to stay one step ahead of the rest. "Freshness of approach and new ideas are crucial to success," says Seedhouse.

Recruitment of regular donors - often by street fundraising teams who sign up passers-by to give by direct debit - is still a mainstay for many charities. Another -yesterday's London Marathon - was set to add millions of pounds to the estimated £200m already raised by charity marathon runners since 1981. However, other old favourites are becoming less productive.

Cathy Pharoah, research director at the Charities Aid Foundation, warns that direct marketing, once a fundraising staple, is "beginning to pall", as an increasingly sophisticated public no longer remains as interested in mailshots. "A lot of it is ineffective," she says. "It's a fast-moving consumer environment."

But Joe Saxton, director of charity thinktank nfpSynergy, says the rewards are there if fundraisers can keep coming up with original ways to engage the public. "There's no such thing as donor fatigue. There's only marketing fatigue.

"The general trend in fundraising approaches is getting something and giving something. We've got the rise of challenge events where the experience of giving is as important as what you give. What we're seeing is a much greater degree of donor involvement in all sorts of ways."

It is this "get something, give something" approach that makes lifestyle and fashion items such a winner for charities that can spot the coming thing. Samaritans' "SamTags" are selling at £2 a time, while also carrying a positive "life matters" message and, importantly, the helpline's phone and website details.

"We very firmly like to mesh communications and fundraising," Seedhouse says. "If you do one without the other, you lose half your strength, you're not doing the job and it's not cost-effective."

If the Samaritans' dog tags catch on among young people - the target audience - other charities may take them up too. This sort of spread of fundraising ideas across the charity sector is what has led aid agency Unicef to take up what Saxton calls "the goat thing".

Unicef fundraising director Fiona Hesselden explains that the goats are part of the charity's "inspired gifts" range, which allows donors to buy goats, water pumps or other useful items to support needy families in Niger, Malawi and elsewhere.

Hesselden says the act of buying something "real" makes the donation "very tangible" for the donor. "The unique selling point is, you really do get what you pay for. It really is a water pump - we've tried to make it as genuine as we possibly can."

The scheme was launched last Christmas after a couple of other charities had begun similar initiatives. Success was swift. So far, it has raised "three times what we thought it would do", says Hesselden.

Other innovations are in the pipeline. Already 70 charities, including Samaritans, the British Red Cross, Scope and Mencap, are signed up to benefit from the new national online lottery, "monday", launched today by commercial firm Chariot UK.

In line with the "get something, give something" principle, players get the chance to scoop up jackpot winnings and will be able to choose which of a selection of charities will receive 30p from every £1 they spend.

Chariot believes the new lottery could raise up to £150m a year for its partner charities - a huge sum. But the project is also notable because it is web-based; it is part of an increasing exploitation of the web for fundraising - a trend that was boosted by the incredible response to the south Asian tsunami.

Cathy Pharoah points out that the tsunami appeal saw many people donate to charity through the internet or by telephone text message for the first time. This will be a big area of expansion in future, she says. "If people are doing their banking or shopping, they're going online. If online shopping and banking can grow, why not online giving?"

Unicef's Hesselden agrees: "I think we're only just beginning to touch the web and work out what it can do for us in fundraising. It isn't a technique - it's a channel. How we make use of it in our fundraising is something we're just starting to look at more creatively."

Both Pharoah and Saxton say "affinity" schemes, where purchase of a commercial product is linked to a charitable donation, are also likely to increase, as part of what Pharoah calls "a wave of ethical consumerism". She points out: "People do enjoy consumption." It is yet another strand of the "get something, give something" strategy.

If successful, the new techniques will spread across the charity world until - as with direct marketing - the public begins to get bored. Then the cycle of new ideas must begin again. But at Samaritans, Rebecca Seedhouse is already looking past the dogtags. "We're planning next year now," she says.